1. FIELD OF THE INVENTION
This invention relates to a method of improving the flavour and/or the mousseux of any kind of sparkling wines by adding amino acids, amino acid derivatives, thiamine and/or thiamine pyrophosphoric acid salt or a material which contains two or more of such substances.
2. DESCRIPTION OF THE PRIOR ART
Wines containing a permanent visible excess of carbon dioxide are called sparkling wines. The nomenclature of the sparkling wines is most complicated. The most famous name "champagne" may be used in some countries only for such products produced in the region of said name in France. Generally, for wines containing a permanent visible excess of carbon dioxide which are produced outside the champagne region of France and made according to cheaper methods than the traditional champagne method, the term "champagne" must not be used and sparkling wines of said kind are e.g. called Sekt, Vin mousseux, Vino spumante, and so on. In the present description the term "sparkling wine" is used to mean any kind of wines conaining a permanent visible excess of carbon dioxide, independent whether said carbon dioxide is produced by a secondary fermentation of sugar or whether it is introduced into the wine by any other method, like e.g. pressing carbon dioxide gas into a wine. Accordingly, with the term "sparkling wine" there are to be understood herein also products which are named "crackling wines" in the United States of America or "vin petillant" in France, or "Perlweine" in Germany. The special organoleptic properties of any sparkling wines are influenced by the method according to which they are produced, and also by the aging of the sparkling wine, especially if they are produced by a secondary fermentation of sugar.
Those products which are most preferred as to their organoleptic properties, i.e. flavour and fragrance, and also as to their mousseux (i.e. the properties of the carbon dioxide contained in the sparkling wine, i.e. the bubble forming properties and foaming properties when the bottle is opened) are those sparkling wines which are prepared according to the traditional champagne method.
The traditional champagne method uses as starting material a wine which is produced by an alcoholic fermentation of musts, i.e. grape juice, which alcoholic fermentation is also called primary fermentation. The primary fermentation of said wine should be complete, that is no sugar should remain in the wine used for making champagne. Furthermore, the wine used for the production of champagne should be rich in acids, it however should have a low volatile acidity, a fruity taste, a white unoxidized colour and a freedom from all undesired odors and tastes. The acid content of the wine should be 6-8% o, corresponding about to a pH-value of 3.0-3.4, and the alcohol content should be in the range of 10-11.5% by volume. One single wine generally does not fullfill all those requirements and therefore as starting material generally a blend of wine is used. To said blend of wines, named Cuvee, there is added a mixture of yeast and sucrose or invert sugar, named tirage. Usually there are added about 24-30 g of sucrose or invert sugar per liter of wine, and the so resulting mixture is then filled into special bottles capable of withstanding a pressure of at least 8 atm, the bottles are sealed, preferably by using a large special cork, and the secondary fermentation is performed in said closed bottles. During the secondary fermentation the added sugar or invert sugar is fermented to form ethanol and carbon dioxide, and as the bottles are closed the carbon dioxide cannot escape from the liquid and remains dissolved in the wine. The wine is aged in the bottles in contact with the yeast for at least 60 days, if however a sparkling wine having an especially good taste and mousseux is prepared, said secondary fermentation is performed for 6 month until 2 or 3 years, since the quality of the sparkling wine improves during this aging in contact with the yeast.
After said aging period the bottles are placed into special racks, and during a period of about 3 to 4 weeks, e.g. 34 days, the bottles are gradually declined in said racks and shaked, so that the bottles are finally in a nearly upside down position in said racks. During the declining and shaking of the bottles in said special racks the bottles are also twisted, generally each day the bottle is twisted around its longitudinal axis for about 45.degree. (1/8 of the circumferential circle of the bottle). During said treatment the yeast generally deposits down onto the cork of the bottle and in the neck. Due to this deposition of the solids, the supernant wine generally gets clear and light. As soon as this is achieved the deposit must be removed. To minimize decreases in this pressure and losses of wine when the cork is removed, the bottles are chilled and the yeast which is deposited in the neck of the bottle is frozen solid by submerging it in a ice-salt mixture or in special freezers. At this temperature the pressure is reduced considerably and when a skilled specialist opens the sealed bottle by removing the cork, the solid plug is ejected, carrying with it the yeast deposit. This step is called "disgorging". To the so resulting raw sparkling wine, which also is called "brut", there is now added the "dosage", i.e. a mixture of sucrose in an alcoholic solution, like e.g. a wine, a brandy or a cognac saturated with sugar. After said "dosage" is added, the bottles are finally closed and aged. Depending whether a "dry" or "sec" sparkling wine, a "demi-sec" sparkling wine or a "sweet" or "doux" sparkling wine shall be produced, there are added such quantities of the dosage that the resulting sparkling wine contains 10-30 g of sucrose per liter sparkling wine.
This traditional champagne method for producing sparkling wines results, if performed properly, in sparkling wines having the most desired organoleptic properties and the typical "bouquet" of champagne or Sekt. Said organoleptic properties are of course dependent to some extent from the wine or blend of wines used as starting material, but still more influenced by the ageing of the raw sparkling wine in contact with the yeast.
Sparkling wines prepared according to said traditional champagne method are very expensive, because of the long ageing periods and the time consuming manual work which has to be performed by specialists.
Several methods therefore have been developped in order to produce a sparkling wine cheaper and avoiding the long ageing periods involved with the traditional champagne method.
One of said methods is the so called "transvasing procedure". In this process the secondary fermentation of the wine or blend of wines after the mixture of yeast and sucrose or invert sugar is added is also performed in closed bottles. Generally the wine is kept in contact with the yeast during this secondary fermentation for about 6 to 8 weeks. In this process however the laborous process of depositing the yeasts in the neck of the bottle and on the cork as well as also the complicated disgorging procedure, in order to remove the yeast deposits is avoided by transferring the content of the bottles including the yeast in a special apparatus called "transvasing apparatus". In this apparatus the gas pressure of the bottles is carefully maintained and to the raw sparkling wine containing still the yeast, there is added the liquid containing the sucrose and the ethanol, i.e. the dosage. This dosage can e.g. be a wine, a cognac or a brandy saturated with sugar. Thereafter there is performed a filtration under a counter pressure, and performing said filtration process, the sparkling wine is drawn off into new bottles, and the new bottles are closed, labelled and shipped. In the step of filtration performed under a counter pressure (counter pressure filtration), generally a pressure in excess of atmospheric pressure of 4.6 atm, i.e. a pressure of 65.4 psig is applied.
A very important disadvantage of the production of sparkling wine according to the traditional champagne method, and also according to the above transvasing process is the risk of bottle breakage during the performance of the secondary fermentation. Bottle breakage is due to defective bottles, and it also occurs when the blend of wines is not properly mixed with the tirage, i.e. the material containing yeast and sugar, so that some bottles receive too much sugar. Because of this excess sugar during the secondary fermentation a higher pressure of carbon dioxide is developed and the bottles break or the cork is ejected.
The above difficulties can be avoided if the sparkling wine is produced by performing the secondary fermentation in a pressure tank. This tank method is cheaper and less hazardous, because in the tank the temperature can be easily controlled by cooling means or heating means and the excess pressure can be allowed to escape. The tank method is performed by adding to the wine or the blend of wines, i.e. to the Cuvee, the tirage comprising yeast and sugar or invert sugar. The secondary fermentation is performed in a pressure tank which generally has a capacity of 500-20,000 liters. The longitudinal axis of said tank can be in horizontal or vertical position, and in the latter case the tank can be easily stirred. Generally the pressure tank is also provided with a water jacket which makes it possible to control the temperature of the tank content during the secondary fermentation by cooling or warming the tank. The secondary fermentation is finished in the pressure tank and the secondary fermentation generally requires about 21 days. After the secondary fermentation there is generally performed a fining or clarifying of the sparkling wine, in order to facilate the separation of the excess of tartrates. If the tank in which the fermentation is performed is provided with a water jacket, then the deposition of the tartrates can be accelerated and facilitated by cooling the sparkling wine in the pressure tank. Such a cooling is also advantageous because if the excess of tartrate is already removed in this step, then a seperation of tartrate from the finished sparkling wine renders unnecessary. After the clarifying step to the sparkling wine there is added the dosage, i.e. the liquid mixture containing the sucrose and the ethanol, e.g. the saturated solution of sucrose in wine or in brandy or in cognac. After the yeast is removed by a filtration applying a counter pressure and during this filtration process the sparkling wine is racked into the bottles applying also a counter pressure. The so filled bottles are then finally closed and submitted to an aging of shorter or longer duration.
A still more economical process for the preparation of sparkling wines is the carbonation method. In this process instead of using the costly process of the secondary fermentation to secure an excess of carbon dioxide in the wine, the carbon dioxide gas as such is added to the wine by impregnation. In said carbonation process accordingly, the step in which the mixture of yeast and sucrose or invert sugar is added to the blend of wines is omitted, and the blend of wines which generally has been clarified by filtration is impregnated under steril conditions with the carbon dioxide. Prior to this impregnation performed in a carbonation apparatus there is generally added to the blend of wines the dosage, i.e. the liquid containing ethanol and sucrose, like a saturated solution of sucrose in wine or in brandy. The main problem in the carbonation process is to secure a good impregnation of the gas in the wine. This can be e.g. accomplished by a counterflow of wine and gas over glass balls or by water carbonation techniques. In the carbonation apparatus there is generally applied carbon dioxide until a carbon dioxide pressure in the wine of 4-6 atm is achieved. Sparkling wines produced according to the carbonation method are generally filled into the same kind of bottles using the same type of cork as for sparkling wines produced according to any of the processes applying a secondary fermentation. In most countries however there has to be stated on the label of the bottle that the sparkling wine is produced by the artificial addition of carbon dioxide.
Sparkling wines having a lower content of carbon dioxide than the sparkling wines prepared according to the above discussed processes are those, which are named in the United States of America "crackling wine", in Germany "Perlwein" and in France "Vin petillant". In Germany, the designation "Perlwein" is used for sparkling wines having an visible excess of carbon dioxide of 1 atm gauge (14.2 psig) at a temperature of 10.degree. C.
It is possible to produce such sparkling wines having a lower content of carbon dioxide, which are in the following designated as "crackling wines" by performing a secondary fermentation of wine in the pressure tank. In this case there is added a mixture of yeast and sucrose or invert sugar to the wine, however generally less sucrose is added, e.g. a quantity of 4-6 g of sucrose per liter of wine. Thereafter the secondary fermentation is performed in the tank as described above. Furthermore, it is also possible to to produce crackling wines by performing the above stated carbonation method, i.e. by impregnating a wine with carbon dioxide gas. The most usual process for the preparation of sparkling wines belonging to the class of crackling wines is to produce the excess of carbon dioxide in the wine by performing the primary fermentation of the musts (grape juice) by applying a pressure. If the primary fermentation of the musts is performed in a controlled way by using a pressure tank, then the carbon dioxide which is produced in this primary alcoholic fermentation remains in the wine. The glucose of the musts is converted by the primary fermentation into ethanol and carbon dioxide, and the pressure tank used for this process prevents that the carbon dioxide can escape from the produced wine, and it therefore remains as excess of carbon dioxide in the wine.
Expensive research work which has been performed in the field of the production of any kind of sparkling wines, including the above described crackling wine, has shown that the typical flavour of champagne and Sekt, i.e. the bouquet of the sparkling wine, is mainly dependent from the contact time of the sparkling wine with the yeasts and not so much dependent from the blend of wines used as starting material. If e.g. the same blend of wines is used and the same kind and quantity of tirage, i.e. the same mixture of yeasts and sugar, is added and the so resulting material submitted to the secondary fermentation, then the flavour and also the mousseux of the produced sparkling wines is dependent from the special performance of the secondary fermentation, i.e. whether it is performed according to the traditional champagne method, according to the transvasing process or according to the tank process. By far the best flavour or bouquet and also the best mousseux is achieved if the secondary fermentation is performed according to the time consuming and expensive traditional champagne method.
The flavouring components, i.e. the substances which are responsible for the bouquet of the sparkling wine were analysed and the results achieved showed that if the contact between the yeast and the sparkling wine during the secondary fermentation is prolonged, then the resulting sparkling wines have a higher content of amino acids. Said amino acids during the ageing procedure are converted partially to aldehydes, partially to alcohols and acids. A longer aging period can result in that the concentration of some alcohols and aldehydes is gradually reduced in the sparkling wine. Such research work e.g. has shown that gradually the concentraton of isobutanol and isopentanol in the sparkling wine is diminished while on the other hand the concentration of heptanol gradually increases.